The present invention relates to a disk array device and a reservation cancellation control method for the disk array device.
For example, in a variety of organizations such as companies, self-governing bodies, or schools, a variety of data of different types is managed in large volumes. These large volumes of data are managed by a storage system formed as a separate entity from a host computer. The storage system is constituted comprising at least one or more storage devices such as a disk array device, for example.
The disk array device is constituted having storage devices such as hard disk drives and semiconductor memory devices and so forth provided in the form of an array, for example. The disk array device supplies logical storage regions based on RAID (Redundant Array of Independent Inexpensive Disks). The logical storage regions are also called ‘logical volumes’ (LU: Logical Unit).
Further, the host computer accesses a logical volume via a communication port of the disk array device, and thus performs data reading/writing (I/O). In order to maintain data conformity and so forth, the host computer sometimes reserves a logical volume and uses the logical volume exclusively. When usage of the logical volume ends, the host computer cancels the reserved state.
Here, in cases where there is a fault with the host computer of any kind in a state where the logical volume has been reserved by the host computer, there is the possibility of the host computer undergoing a system fault in a condition where the reserved state has still not been cancelled. In such a case, another host computer is unable to use a logical volume that is still placed in a reserved state. Therefore, for example, the power supply of the disk array device is shut off, the cable connected to the communication port is disconnected, and the power supply of the channel switch connected to the disk array device is shut off, whereby reset processing is performed and the reserved state is cancelled.
A technology according to which, when a host whose disk device is reserved hangs up, a response confirmation is performed between a disk control device and the host, and, in cases where there is no response from the host, the reserved state is forcibly cancelled, is known (Japanese Patent Application Laid Open No. 5-189396).
When reset processing is performed by shutting off the power supply of the disk array device in order to cancel the reserved state of the logical volume, the host computer is unable to utilize storage services until the disk array device is restarted. Further, in cases where reset processing is performed by shutting off the power supply of the channel switch and disconnecting the cable connected to the communication port, another host computer is then unable to access another logical volume via the port that has been reset.
In recent years, in keeping with the increased performance and higher capacities of disk array devices, there have been frequent cases of disk array devices being used by a multiplicity of host computers. A plurality of logical volumes can each be associated with a plurality of respective communication ports that a disk array device comprises. Therefore, when the communication port is reset in order to cancel the reserved state that still remains for a logical volume, it is also no longer possible to access another logical volume associated with the communication port.
Further, when a communication port is reset by a disk array device and a reserved state that remains for a logical volume is canceled, another host computer is unable to identify the fact that the reserved state has been cancelled. Therefore, there is also the risk of a discrepancy in identification relating to the presence or absence of a reserved state between the disk array device and a multiplicity of host computers.
Further, the technology described in Japanese Patent Application Laid Open No. 5-189396 cancels the reserved state of a disk device but is unable to cancel the reserved state for a logical volume that is provided on the disk device. Therefore, the conventional technology cannot be applied to a system in which a logical volume is reserved and accessed.